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(11) | EP 0 488 315 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | A balanced cascode current mirror |
| (57) A balanced cascode current mirror includes a first and second current paths respectively
defined by first and second transistors and by third and fourth transistors. Each
current path may include the sources and drains of the transistors in such path. Connections
may respectively extend between the gates of the first and third transistors and between
the gates of the second and fourth transistors to provide the first and third transistors
with substantially identical source, gate, and drain impedances. An input current
is introduced to the drain of the second transistor and an output current with substantially
identical characteristics is obtained from the drain of the fourth transistor. A capacitance
may be connected between the drain of the second transistor and the gate of the first
transistor to produce a flow of a current at high frequencies through the first current
path corresponding to the input current at the drain of the second transistor. A fifth
transistor may be connected in a circuit with a constant current source to regulate
the current through the first and second transistors to be substantially equal to
the input current at low frequencies. The gate of the fifth transistor may be connected
to the drain of the second transistor, and the source of the fifth transistor may
be connected to the gate of the first transistor, to provide this current regulation.
The gates of the second and fourth transistors and the drain of the fifth transistor
may have a common reference potential such as ground. |